Got inserts in the mail that I'd bought on eBay last week, gave them a try. The cutter is a Walter F4042R.UW19.019.Z03.10, a 3/4" 3-insert 'end mill", and takes ADMT/ADHT/ADGT 10T3xx style inserts. I had gotten it about 6 months ago, never bought inserts because I had an equivalent Kennametal cutter that did have inserts. I sold if off because this one is a far newer and better cutter. Greater axial shear angle, greater radial rake angle for lower cutting forces. This is an important consideration on low HP machines like mine.

The inserts, Walter ADHT10T3PER-G88 grade WK10. Highly polished, dead sharp.


The cutter, showing the angles. Axial shear angle a little harder to discern due to poor lighting conditions in my shop.




So I snugged it up in a 3/4" R8 collet, threw a piece of 6061 aluminum in the Kurt vice and took two cuts of .100" (2.5mm) deep. Cranked the spindle up to max 4500 rpm. I calculated that this was 883.5 surface feet per minute cutting speed. Looking to see what kind of finish I would get and knowing the limited HP (2), I then multiplied the RPM (4500) x the feed per tooth (0.003") x the 3 inserts for 40.5 inches per minute feed rate. In my machine control's "manual power feed" mode, the closest is 40.0 ipm, close enough.

The first pass was .25" wide, to check spindle load. No decrease in rpm detected. The second pass was the same .100" deep, but 0.375" wide, so half the cutter diameter. It just started sounding off some strain but didn't seem to slow.





The finish looked pretty darn good! I figure (using my surface finish comparator) that it's between an 8 and 12 Ra (microinch), though it may look a little rougher in the photos.